Photosensitive material comprising a furfurylidene, a lower haloalkane and poly-n-vinyl carbazole

ABSTRACT

A heat-developable photographic plate which comprises, on a support, a layer containing: as a color former, a furfurylidene compound; as a sensitizer, a lower haloalkane; and, as a color enhancer and binder, poly-N-vinyl carbazole. The plate is capable of forming, after exposure to light, dense, black images at temperatures between about 100*-150*C.

United States Patent 1191 [111 3,907,570

Robie Sept. 23, 1975 PHOTOSENSITIVE MATERIAL 3.697.276 10/1972 Lewis etal 96/90 R COMPRISING A FURFURYUDENE A 3.773515 ll/l973 Yamashita et al.96/90 R LOWER HALOALKANE AND POLY-N-VINYL CARBAZOLE [75] Inventor: SusanP. Robie, Gorham, Maine [73] Assignee: Scott Paper Company,Philadelphia.

[22] Filed: Mar. 19, 1974 [2]] Appl. No.: 452,596

[52] US. Cl 96/90 R [51] Int. Cl. G03C 1/52 [58] Field of Search 96/90 R[56] References Cited UNITED STATES PATENTS 3,394,395 7/1968 Mattor etal, 96/90 R Primary E.raminei=-Won H. Louie, Jr. Attorney, Agent, ofFirm.lohn A. Weygandt; John W. Kane, Jr.

[57] ABSTRACT A heat-developable photographic plate which comprises, ona support, a layer containingz'as a color former, a furfurylidenecompound; as a sensitizer, a lower haloalkane; and. as a color enhancerand binder, poly-N-vinyl carbazole. The plate is capable of forming,after exposure to light, dense, black images at temperatures betweenabout lOO-l50C.

1 Claim, N0 Drawings Laridon et al. 96/90 R BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates tophotosensitive materials.

More particularly, it relates to a negative-working,thermally-developable and fixable photographic plate comprising, on asupport, a purified furfurylidene compound, a tertiary amine and aphotosensitive lower haloalkane.

2. History of the Prior Art In U.S. Pat. No. 3,394,395 granted July 23,1968, there is disclosed and claimed a photographic medium consistingessentially of a transparent to translucent plastic film containingdissolved therein a furfurylidene compound as the color formingingredient, a primary aromatic amine enhancer, and a lower haloalkanesensitizer, e.g., iodoform. The photographic medium is negative workingand is usually carried as a film on a support thereby forming aphotographic plate. Permanently'black or colored images can be producedby the process disclosed therein by short exposures of the photographicmedium to light directed through an image-containing transparency. Anunusual feature is that no chemical treatment is required to develop theimage or to desensitize the unexposed or background areas. All that isrequired to develop the image is to heat the medium briefly to aboutl()()150C. I

It is stated in U.S. Pat. No. 3,394,395 that it appears that thealdehyde groups derived from the furfurylidene react with the aminegroup of theenhancer. In every case tested, secondary and tertiaryaromatic amines have failed to give color enhancement of the image. Thisindicates that one essential reaction for color formation in the presentinvention is the reaction of primary amine groups.... Column 2, linesl5.

SUMMARY OF THE INVENTION -vinyl carbazole replaces both the enhancer andbinder components of the prior art composition.

DETAILED DESCRIPTION Poly-N-vinyl carbazole, also known as poly (9-vinylcarbazole), is commercially available and may be represented by theformula In general, the haloalkane sensitizer used in the presentinvention is a solid at room temperature and has a purity of at least98%. Compounds containing 1 to 2 carbon atoms, such as iodoform andpentabromethane, are preferred. The furfurylidene color-former'isusually prepared by reacting furfural with a suitable amine, in the caseof the furfurylidene imines, and with a suitable glycol or higherpolyol, in the case of the cyclic acetals. Conventional organicsynthesis techniques are used, as more fully described in U.S. Pat. No.3,394,395.

The furfurylidene color-former, the haloalkane sensitizer and thepoly-N-vinyl carbazole are applied to a suitable support insolventsolution. Any one of several suitable organic solvents that are volatileat room temperature or at slightly elevated temperatures can be usedsuch as chloroform; benzene; 1,1,2 trichloroethane and methyl ethylketone. Mixtures of the solvents can be used to obtain improvedsolvation.

While the polymeric tertiary amine of the present invention offers theadvantage of replacing both. the enhancer and binder components of theprior art composition, other filmforming resins may be included in thecoating formulation if desired. Such a film-forming resin should beessentially non-reactive with the other ingredients of the solution anddesirably in its pure state forms a translucent or transparent film thatis colorless or substantially colorless so as not to interfere with ormask the color produced by the other ingredients in the photographicmedium. Some polyester polymers have been found to be unsatisfactorypresumably because the hydrogen iodide attacks the ester linkage. Thepolymer should be unaffected by concentrated aqueous solutions ofhydrogen iodide at 25C. In most cases it is desirable for the polymer toform a non-tacky film. Preferred polymer film-formers or binders includepolyphenylene oxide and polystyrene. I The weight ratio of poly-N-vinylcarbazole to the furfurylidene color-former is usually in the range of lto 1 to 5 to l, and when the poly-N-vinyl carbbazole is used as the solebinder preferably 5 to 1. The weight ratio of haloalkane sensitizer tocolor-former is in the range of l to 10 through 20 to 1, preferably 1 to2 through 2 to l. The coating solids used will normally be in the rangeof 10 to 20 percent. A photographic plate is prepared from the coatingsolution by applying it to a suitable support by conventional means toproduce, upon drying, a coating weight of 3 to 15 g/m or a filmthickness of 1 to 10 microns. Other things being equal, the thicker thefilm, the more intense the image.

The support used in the preparation of a photographic plate may requirea coating on its surface to prevent the penetration of organic solvents.In the case of paper, starch and potassium polyacrylate resins andsimilar binders will accomplish this function. In general, water solubleresins that are film-formers can be expected to give adequate solventhold-up. In the case of transparent supports, films of polyethyleneterephthalate resin (DuPonts Mylar) have proved to be excellent supportsand particularly suitable for the preparation of films formicrophotographic copying. In cases where transparent supports are notdesired, any impermeable inert support such as aluminum, sheet steel,glass, etc. may be employed.

These and other principles, features and advantages of the presentinvention will become more fully understood fromv a consideration of thefollowing examples.

EXAMPLE I A photographic plate was prepared from a coating solutioncomprising:

Parts by Weight dissolved in an amount of a solvent consisting of 60% byvolume methylene chloride and 40% by volume trichloroethylene sufficientto form a solution having 18% solids by weight.

The solution was applied in an amount equal to 7.5

'g/m by dry weight to one side of a suitably barrier EXAMPLE ll Aphotographic plate was prepared from a coating solution comprising:

Parts by Weight poly-N-vinyl carhazole 3.0 difurfurylidenepemaerythritol 3.0 iodoform 4.0 poly phenylene oxide 8.0 a-methylstyrene 8.0

dissolved in an amount of the mixed solvent described in Example l toform a solution having 18% solids by weight. This solution was appliedin an amount equal to 13.75 g/m by dry weight to one side of a suitablybarrier coated paper sheet, and dried.

A second photographic plate was prepared from a coating solutioncomprising:

Parts by weight difurfurylidene pentaerythritol 3.0 iodoform 4.0 polyphenylene oxide 8.0 a-methyl styrene 8.0

This coating formulation was made up and coated in the manner describedabove.

Both the plate containing poly-N-vinyl carbazole and the platecontaining no amine were exposed under the lamp described in Example Ifor one minute and heat developed as in Example .I. I

The results indicated that the plate containing poly- N-vinyl carbazolewas'five times as sensitive to light as the plate containing no amine.The imaged plates were then subjected to accelerated aging-7 days at38C. While the image formed on the plate containing the poly-N-vinylcarbazole was slightly faded, the image on the plate containing no aminehad completely disappeared.

While the invention has been described with reference to preferredembodiments thereof, it is understood that various other changes andmodifications thereof will occur to a person of ordinary skill in theart without departing from the spirit and scope of the invention, asdefined by the appended claims.

What is claimed is:

l. A heat-developable photographic plate comprising, on a support, alayer containing: as a color former, a purified furfurylidene compound;as a sensitizer, a photosensitive lower haloalkane; and, as a colorenhancer and binder, poly-N-vinyl carbazole.

1. A HEAT-DEVELOPABLE PHOTOGRAPHIC PLATE COMPRISING, ON A SUPPORT, ALAYER CONTAINING: AS A COLOR FORMER A PURIFIED FURFURYLIDENE COMPOUND,AS A SENSITIZER, A PHOTOSENSITIVE LOWER HALOALKANE, AND, AS A COLORENHANCER AND BINDER, POLY-N-VINYL CARBAZOLE.